First ranked

Level and hours played has zero correlation with MMR.

The only way to tell anything about your overall skill pre-calibration (and it's an estimate at best) is looking at your dotabuff and seeing whether your matches are "normal skill," "high skill," or "very high skill." Many matches won't have a bracket labeled at all, but some of them should.

I don't know where the normal-high divider is, I calibrated at 3300 and that was considered high. The high-very high divider seems to be around 3800-4000.

Either way it doesn't matter at all when you calibrate - you're working through the same ranks, the only difference is whether or not you are aware of it at the time.